Jacob Weisberg is chairman and editor-in-chief of The Slate Group and author of The Bush Tragedy. Follow him on Twitter.

This minor incident, which barely rated as news for a few political blogs, offers a glimpse of Christie's personality, which seems increasingly grumpy and snappish. But it says even more about the current state of the national Republican Party, where magical thinking trumps rationality, and even to acknowledge basic realities about the world we live in runs the risk of damaging one's political future.

Christie is not part of the natural constituency for Darwin-denial. He's an intelligent man, a lawyer, a fiscal rather than a social conservative. But Christie is also someone who might want to run for president someday, or be selected as someone's running mate. For those purposes, he must constantly ask himself the question: Am I about to say something to which a white, evangelical, socially conservative, gun-owning, Obama-despising, pro-Tea Party, GOP primary voter in rural South Carolina might object? By this standard, simple acceptance of the theory of evolution becomes a risky stance. To lie or to duck? Christie chose the option of ducking while signaling his annoyance at being put in this ridiculous predicament.

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Moments like this point to a growing asymmetry in our politics. One party, the Democrats, suffers from the usual range of institutional blind spots, historical foibles, and constituency-driven evasions. The other, the Republicans, has moved to a mental Shangri-La, where unwanted problems (climate change, the need to pay the costs of running the government) can be wished away, prejudice trumps fact (Obama might just be Kenyan-born or a Muslim), expertise is evidence of error, and reality itself comes to be regarded as some kind of elitist plot.

Like the White Queen in her youth, the contemporary Republican politician must be capable of believing as many as six impossible things before breakfast. Foremost among these is the claim that it is possible to balance the federal budget without raising taxes. Most Republican politicians are intelligent enough to understand that with federal revenues at 14.4 percent of GDP and expenditures at 25.3 percent, it is, in fact, impossible to close the fiscal gap with spending cuts alone. But GOP candidates acknowledge this reality at their peril. Grover Norquist, the right-wing lobbyist and former collaborator of Jack Abramoff's, has appointed himself chief enforcer of the party's anti-tax catechism. If Republican candidates won't sign his no-new-taxes pledge, Norquist and fellow inquisitors at the Club for Growth threaten them with excommunication, social death, and the punishment of being "primaried" by a well-funded conservative challenger.

Reality-denial is not limited to the Republican inability to utter words like evolution and revenue. The long-range forecasts in the Paul Ryan plan, which show spending falling to 3 percent of GDP to allow for additional tax cuts, express an impossible libertarian fantasy. So too does the current Republican effort to bring this utopia about by refusing to raise the federal government's credit card limit. It is not a matter of conjecture, but something closer to a universal understanding among economists, that failing to raise the debt ceiling could cause another global economic crash. The plutocratic populist Donald Trump recently answered this objection on behalf of the party. "What do economists know? Most of them aren't very smart."

Another series of Republican fictions relates to climate change. This starts, at one extreme, with the outright denial of Michele Bachmann, progressing through the various "not-man-made" and "the jury's-still-out" dodges offered by the likes of Sarah Palin and John Thune. Christie handled this issue in the same evasive way he did the evolution question, albeit with less aggression, shortly after being elected. "I'm skeptical—I'm skeptical," he said. "And you know, I think at the end of this, I think we're going to need more science to prove something one way or the other." The conservative press has gone after Newt Gingrich merely for saying the country must do something to address climate change. But if you're one of the conservatives who had the misfortune to accept science during the pre-Tea Party era, don't worry–you can still escape extinction by expressing doubt about any possible solution. This describes the position of Mitch Daniels; Mitt Romney; and Tim Pawlenty, who once supported cap-and-trade but has simply reversed himself, offering a self-flagellating apology and confession ("it was stupid").

Then there are all the mundane, material facts that Republicans choose to "doubt." The market in Obama lies has moved in rough parallel to the recent silver bubble. Over a period of months, the paranoid and foolish bought in, driving up the price. Republican candidates tried to find sly ways to signal skepticism about the President's American-ness and Christianity without sounding like complete imbeciles. Then Donald Trump, for whom that's not a problem, started buying in bulk. This infuriated the outflanked Sarah Palin, who used to have this wackadoodle territory to herself. Then President Obama released his long-form birth certificate, the bubble burst, and Trump was publicly ruined at the White House Correspondents' Dinner. With birther sentiment deflated, Palin has moved on to a new, no less idiotic slander, that William Ayers *, the former Weather Underground leader, might have written Obama's memoirs.

Even after the release of Obama's birth certificate, however, nearly one-quarter of Republicans still refuse to believe that the president was born in the United States. Conspiracy thinking is flourishing on the right like no time since the McCarthy era. The GOP rank and file is in desperate need of a cold shower, a slap in the face, a wake-up call. But instead of telling the base to get a grip on reality, the party's leaders are chasing after the delusional mob. To get to the front of the line in 2012, Republican candidates must pretend to believe a lot of nonsense than isn't so. Or do they actually believe it?

Correction, May 20, 2011: This article originally misspelled William Ayers' surname. (Return to the corrected sentence.)